best amount of time to fast?

HI

I am on a 10 day water fast. I see that some of you are on 14 days and others on 80-20...

I am curious - how do you pick the amount of days to fast?
it must depent on sickness no?
or amount of weight desired to lose?

I started at 138 and am down to 128
5 lbs = shit that was inside me
about 4-5 probably = water weight..

My stomach is TOTALLY FLAT - I LOVE IT, but always happens when I fast, I chose to fast on water this time because I want to GET RID of the celulite on my butt and just under it!

PROBLEM!

I am runnin a marathon well, a 1/2 on saturday and a FULL on sunday around the 12-13 of January....do you think I should keep fasting and would JUICE be enough??

WHen does the fast actually halp you lose FAT instead of feces and water weight???

WIll I ever see a decrease in the celulite??